BOSTON, MA – AUGUST 23: Pitcher Garrett Whitlock #72 of the Boston Red Sox shouts out after ending the 11th inning against the Texas Rangers at Fenway Park on August 23, 2021 in Boston, Massachusetts. (Photo By Winslow Townson/Getty Images)

It’s not an uncommon tale for relievers who transition into starting pitchers to never regain their old form. Joba Chamberlain and Neftalí Feliz are prominent examples that come to mind in terms of elite relievers, whose transition into starting pitchers lead to injury and inconsistency throughout the rest of their careers. The Red have their own history in failing to transition elite relivers into starters such as Daniel Bard. Bard never fully recovered mentally from failing to transition into a starting pitcher. A current example is Jordan Hicks. Since transitioning back into a reliever after making nine starts in San Francisco, Hicks has posted an 8.20 ERA in Boston. 

On the other hand, Garrett Whitlock, is having an incredible resurgence after three injury-riddled seasons, going back and forth between the Red Sox rotation and bullpen. Earlier this year, it felt like Whitlock was at a career crossroads. After a dominant rookie season, he posted a 1.96 ERA in 73.1 innings, with 19 multi-inning appearances. Following an outstanding rookie season, Whitlock was signed to a four-year extension worth $18.75 million with the idea of moving him into the starting rotation. In his sophomore season, Whitlock appeared in 31 games, making nine starts. He posted a 4.15 ERA in 39 innings as a starting pitcher and a 2.75 ERA in 39.1 innings as a starting pitcher. He also had two trips to the IL due to problems with his right hip. In 2023, Whitlock posted a 5.15 ERA in 32 appearances in the hybrid starter-reliever role. He also had two IL stints, but this time with right elbow issues. In 2024, Whitlock made four starts, posting a 1.96 ERA, but underwent season-ending UCL surgery on his right elbow in May. It was his second UCL tear of his career; the first was in 2019, which required Tommy John surgery. Following a second elbow surgery, Whitlock seemed destined to be one of those talented pitchers ruined by the injuries and mental toll from transitioning from a reliever to a starting pitcher. However, he has managed to return to his dominant 2021 form and help the Red Sox turn around their bullpen.

In 2024, Boston relievers combined for a lackluster 4.39 ERA, ranking 24th out of 30th in baseball. Through 144 games, Boston’s bullpen has been a strength for the team, posting a 3.45 ERA, ranking 3rd in baseball and the best in the American League. Whitlock has played a crucial role in the bullpen’s success as Boston’s primary setup man. In 2025, Whitlock has made 56 appearances out of Boston’s bullpen. Over 65.1 innings of work, he has posted a 2.48 ERA. The 29-year-old right-hander is one of six relievers in baseball with 22+ holds and an ERA below 2.50 along with Abner Uribe, Jason Adam, Tyler Rogers, Bryan Abreu and Brad Keller. Whitlock’s 11 multi-inning appearances are more than the other five relievers combined. When healthy, Garrett Whitlock is a uniquely valuable bullpen arm for Boston. 

Fifty-one of Whitlock’s 56 appearances this season have come in the 7th inning or later with a 2.41 ERA. Without his bounce-back season, who knows where the Red Sox would be this season? Liam Hendricks only appeared in 14 games before going back on the IL. Justin Slaten went down with shoulder inflammation on June 1st and missed three months. Jordan Hicks’ tenure in Boston has been a disaster. Whitlock may be having the second-best season in the Red Sox bullpen behind Aroldis Chapman Whitlock deserves to be recognized as Boston’s most valuable reliever.